1. Technical Field
The present invention relates to hand tools for cutting, and more particularly to a hole saw having the advantages about low manufacturing costs, short production cycle, and firm structure.
2. Description of Related Art
FIG. 1 shows a conventional hole saw set 1, which comprises a rotary machine (not shown), a hole saw 2, a drill 3, and a connector 4 connecting the three above together, so that the hole saw and the drill can be driven by the rotary machine to perform rotation. In use, the drill is first placed on the center of the site to be drilled on a workpiece, and the rotary machine is activated to rotate the drill and the hole saw, making the drill bore and get positioned on the workpiece. Afterward, the when the hole saw comes to abutting against the workpiece, the hole cutting operation is started.
Therein, the hole saw comprises a cover plate 5 and a circular saw blade 6. The cover plate has its outer periphery aligned and soldered with the outer periphery of the circular saw blade using a solder 7 by means of soldering. For making the solder joint neat and for preventing the solder from contacting the hole, the solder joint is preferably ground to level. However, after the foregoing grinding operation, there is merely a little solder residual between the soldered cover plate and circular saw blade in addition to the thin layer of solder left on the outer periphery of the soldered assembly. When the hole saw set 1 is later put into use, the counterforce applied to the circular saw blade by the workpiece being cutting may be large enough to overcome the limited binding force between the cover plate and the circular saw blade, making the circular saw blade coming off the cover plate. As a result, the workpiece may be damaged and even the operator can be injured. Hence, there is a need to improve the combination between the cover plate and the circular saw blade.
In view of this, the present invention is made to improve the conventional hole saw.